Homebrew PCBs

On Sat, 20 Dec 2008, William Alford wrote:

> At 01:29 PM 12/19/2008, you wrote:
>> Does anyone know if I would get away with drilling glass with a
>> standard tungsten carbide drill bit set. The spindle speed of my mill
>> goes up to 60krpm.
>
> i've drilled glass and ceramic tile and stone. you need to drill
> *slowly*. and spray repeatedly with water to keep cool and remove
> residue. i've used tungsten carbide bits (can get at home depot in a
> few sizes) and they do work but have a short lifetime. i got about 6
> - 10 holes per bit before wearing out. most of my drilling was in
> 1/4" glass and granite, so i don't know what thickness you intend.
> diamond bits are better, but still require water to last.

I have a book somewhere that describes making a drill bit by mounting a 
copper or brass tube on a steel mandrel.  Cut two V-shaped notches in the 
business end.  A clay dam is built up around where the hole will go. 
Pour an abrasive slurry in there and carefully lower the drill.  Top up 
with water/slurry as needed.

-- 
David Griffith
dgriffi@...

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